Variable Displacement Hydraulic Pump System with Flow Combining
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Solution Overview
Problem
Conventional hydraulic systems face inefficiencies due to pressure losses from fluid restriction for actuator speed control, and existing meterless systems are limited in simultaneous operation of multiple actuators and flexible speed and force control.
Innovation Solution
The hydraulic system employs variable displacement pumps in closed-loop circuits, allowing for combined fluid flow between circuits to meet demand, enabling simultaneous operation of multiple actuators with independent speed and direction control through combining and switching valves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional hydraulic systems use fluid restriction to control actuator speed, then actuator speed can be independently controlled, but pressure losses occur that reduce overall system efficiency
Solution Approach 1:
The system employs variable displacement pumps that can dynamically adjust their flow output to match the actual demand of actuators, replacing static fluid restriction methods with dynamic flow control at the source, thereby eliminating throttling losses while maintaining independent actuator speed control
Solution Approach 2:
The patent changes the fundamental parameter of fluid flow control from restriction-based (conventional) to demand-based (meterless), where pumps adjust their displacement to deliver exactly the flow needed, transforming the system from energy-losing throttling to energy-efficient direct supply
2Loss of energy
If meterless hydraulic systems use pump operation to control actuator speed, then system efficiency improves, but the ability to operate multiple actuators simultaneously is limited
Solution Approach 1:
Each variable displacement pump in the system is designed to serve multiple functions: it can supply its primary actuator and also provide supplemental flow to other actuators through combining valves, making each pump a multi-functional resource that can be dynamically allocated based on system demands
Solution Approach 2:
The system merges the flow outputs of multiple pumps through combining valves to meet the demands of actuators, allowing simultaneous operation of multiple actuators by combining flows from different pump-actuator circuits rather than requiring sequential operation
3Device complexity
If fixed displacement motors are used in travel and swing circuits, then system simplicity is maintained, but speed and rotation direction control flexibility is reduced
Solution Approach 1:
The patent replaces fixed displacement motors with variable displacement motors in travel and swing circuits, enabling these actuators to dynamically adjust their speed and rotation direction independently of pump characteristics, providing flexible control while maintaining system efficiency through demand-matched flow delivery
Data Source
AI summary
A method of controlling a hydraulic system includes providing fluid to a first actuator with a first pump via a first closed-loop circuit of a machine, and providing fluid to a second actuator with a second pump via a second closed-loop circuit of the machine. The method also includes providing fluid to a third actuator with a third pump via a third closed-loop circuit of the machine, and providing fluid to a fourth actuator with a fourth pump via a fourth closed-loop circuit of the machine. The method further includes forming a combined flow of fluid including fluid from the first circuit and fluid from at least one of the second, third, and fourth circuits, and directing the combined flow to the first actuator while providing fluid to the actuator of the at least one of the second, third, and fourth circuits.